1. Field of the Invention
The present invention relates to a gasoline preheater for internal combustion engines, and more particularly to a method and system for preheating gasoline to an optimum temperature for most efficient vaporization and combustion.
2. Description of the Prior Art
It has been well known in the prior art to preheat gasoline before introduction of the fuel into the carburetor. It is also well known to utilize the heat of the engine coolant to perform this function. A typical U.S. Pat. which discloses this concept is No. 4,083,340 issued to Furr, et al. Furr notes a number of earlier patents which also dealt with this problem. Furr teaches the use of a superheater having a chamber through which the gasoline passes on its way from the storage tank to the carburetor with a copper coil disposed within the chamber through which heated coolant from the radiator of the engine is passed. An orifice is included in the line carrying the hot liquid coolant which is calibrated to provide a desired flow of coolant to heat the fuel to a preselected temperature. Although Furr states that the calibrated orifice can be changed to select the desired gasoline temperature, he states that the superheater increased the gasoline mileage on automobiles tested when the temperatures were maintained at any selected temperature from 100.degree. to 225.degree. F. but notes that the best results depend on the composition of the gasoline being used. He found that about 140.degree. F. was optimum in his tests.
I have investigated the use of preheaters for improving the performance of gasoline engines and have found that the temperature of the fuel is quite critical with present day gasoline compositions. One problem which apparently has not been forseen by Furr or by any of the other prior workers in this field is that the ambient air temperature, the load on the engine, the location of the fuel pump and fuel lines in relation to the exhaust manifold, the amount of cooling air from the engine fan, and similar factors often control the minimum temperature of the fuel. For example, if the device of Furr were used in a high performance engine operating under heavy loads in hot weather and a desired temperature of 140.degree. F. was required, it is quite possible for the fuel to be at a higher temperature from the engine heat as well as the ambient air temperature. Therefore, the superheater of Furr would be useless.
Another problem with the Furr-type device is that the selected fuel temperature is not easily controlled. For example, I have found experimentally that present day fuel compositions produce optimum fuel economy when the fuel in the carburetor float chamber is about 120.degree. F. Thus, it is apparent that the gasoline producers vary their volatile components from time to time. To change the Furr superheater temperature, it would be necessary to disassemble the device and to replace the calibrated orifice. The use of the calibrated orifice also assumes that the coolant temperature is constant and the flow of that coolant is constant, a situation that would seldom, if ever, be realized in a practical automobile.
Thus, there is a need for a gasoline preheater which can accurately control the temperature of the fuel as it flows into the carburetor, which is easily adjustable to suit the composition of the fuel being used, which will not be influenced by engine and ambient heat, and which provides a means for accurately maintaining the correct temperature.